Safety ski binding



Jan. 12, 1943. A. MclLVAlN E I v 2308338 SAFETY SKI BINDING Filed March11, 1 941 2 Sheets-Sheet l YAVAVNAVAV l V JN V V Y wV IIIIII 58 I 1 252/86 N I d 35 ATTORN EY Jan. '12, 1943,

A. MclLvAl NiE- 2,308,338

SAFETY SKI BINDING Filed March 11, 1941 2 Sheets-Sheet 2 ATTORNEYPatented Jan. 12, 1943 UNITED STATES PATENT orrice Alexander Mcllvaine,New York, N. Y.

Application March '11, 1941, Serial No. 382.733

11 Claims.

This invention relates to improvements in ski bindings.

The principal object of the invention is to make the sport of skiingsafer than it now is by providing bindings which will secure the skisfirmly to the skiers boots during .ordinary running and in the executionof normal turns, and which will function automatically to release theboots whenever the twisting strains upon the skiers legs are such thatif continued or exceeded might very well result in a bad sprain or inthe breaking of a bone.

It is a more specific object of the invention to provide a safetybinding of the foregoing character having a clamping element which,though serving normally to hold the toe portion of a boot againstlateral movement upon the ski, will yield and spread apart when thepressure upon it exceeds some predetermined safe limit to permit theboot to free itself from the ski and immediately relieve the skiersankle of further strain.

It is yet another object of the invention to provide safety bindings inaccordance with the foregoing having yielding connections between theirtoe clamping .elements and the skis which may be adjusted by theindividual user to release his boots under lateral stresses which forhim may be dangerous. The novice who can expect to fall frequently maythus set his bindings .to free his boots whenever .his ankles aresubjected to the slightest excess strain, whereas the more skilled.skier who can avoid many hazardous situations may wish to adjust hisbindings for release at a much higher limit. In each case, however, theadjustable character of the bindings permits the release to occur undercircumstances which may represent real danger for the particularindividual who is using them.

The foregoing and other objects of the invention, as well as variousfeatures thereof, will be better understood from a consideration of thefollowing description in the light of the accompanying drawings inwhich:

Fig. 1 is a side elevational view of a fragment of a ski having a bootsecured to it by means of the binding device of the present invention;

Fig. 2 is a plan view on an enlarged scale, of the ski of Fig. 1 and ofthe toe clamp portion of the binding, certain parts thereof being brokenaway better to show underlying ones;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is an end view illustrating a portion of the toe clamp of thebinding and the manner in which it engages the ski boot; and,

Figs. 5 and 6 are plan views of a portion of a toe clamp embodying theinvention in ,a modified form.

In the drawings and referring to Fig. 1, the numeral 9 designatesgenerally a resilient strap iii) element which is adapted to engage thegrooved heel I0 of the ski boot II and to urge the toe portion of theboot into the tapered recess beto be capable of yielding when thelateral -pressure applied to them by the ski boot exceeds somepredetermined value. Under such circumstances they spread apart, and byrelieving the boot of latera1 support, permit it to slip out of thebinding under the urging of the resilient strap element. The yieldingtoe clamp thus serves automatically to release the skiers foot wheneverit or his leg or ankle is subjected to dangerously high stress.

One preferred form of yielding toe clamp for such'a binding, asillustrated in Figs. 2 and 3, comprises a pair of upright toe irons l2having lateral flanges l5 which are pivotally connected at their forwardends, as indicated at It, to base plates I1, and are normally heldagainst swinging movement by the engagement of spring pressed pawls ISwith the notches l9 formed in the rear edges of their lateral flanges.In this form of the invention the pawls are mounted upon leaf springs 20having their inner ends riveted or otherwise secured to lugs 2| whichmay be conveniently struck up from the base plates, and their outer endsbacked by adjusting screws 22 threaded through similar lugs 23, whichscrews extend outwardly from the toe clamps so as to be readilyaccessible.

The toe irons are preferably mounted upon separate base plates l1, andare secured to the ski M in such manner that their positions may beadjusted to receive boots of different sizes. One way of accomplishingthis is to serrate the ends of each of the base plates, as indicated at24, and to form matching serrations in the underside of a cover plate 25which is adapted to be fastened to the ski by means of screws 28 or inany other desired way. Thus, when the base plates have been set upon theski in desired positions, their serrated ends will be engaged by thematching serrations of the cover to prevent lateral movement betweenthese various elements.

The pawls it serve to hold the toe irons in such normal positions as toengage the sides of a ski boot and to support it laterally underpressures which are no greater than those encountered in ordinary skiingactivity. When, however, the sidewise pressure upon the irons exceedswhat may be called a safe value, the sloping cam surfaces of theirnotched portions l9 react against ing or decreasing the limit at whichthose elements will release the toe irons.

Under certain circumstances both of the irons will give way to releasetheir hold upon the boot.

Usually, however, the pressure upon one of them will be greater thanupon the other, and only that iron will yield. But whether one or bothof the irons are released to swing about their pivots, thespacingbetween them will be increased to relieve the boot of lateral supportand to allow it to separate from the ski.

While a very considerable force must be applied to the toe irons toeffect their release, they may be returned and relocked in their normalpositions by the application of a much lighter pressure. Thus, wheneither one or the other of the irons is swung inwardly, the rounded edge45 of its lateral flange engages the opposing rounded outer edge 46 ofthe cam l8, and forces the cam gently backwards against the reaction ofthe spring until it reaches such a point that it may snap back into thenotch Hi to lock the toe iron in normal position.

Another form of yielding toe clamp is illustrated in Figs. and 6. Thedifferences between this structure and that illustrated in Figs. 2 and 3are to be found primarily in the construction of the spring pressedpawls which serve to hold the toe irons in their normal positions.Accordingly, Figs. 5 and 6 illustrate only a fragment of the completetoe clamp and reference may be had to Figs, 2 and 3 for an understandingof the details which are not shown. In this form of the invention thepawl [8a is mounted upon the front surface of a leaf spring 20a which issupported between oppositely disposed lugs 21 and 28 of the base plateIla. The spring is held against lateral movement by its inturned ends 29which engage the lugs 27, and it will be noted that these ends are bentinwardly to such an extent as partially to overlap the main body of thespring.

Accordingly, when that element is bowed in a rearward direction, its endportions can move between the lugs without binding. The spring will, ofcourse, be held down upon the base plate by the overlying cover plate25.

The pawl lBa has two cam faces 30 and 3|. of which one is considerablysteeper than the other. In Fig. 5 the spring element is so disposedbetween its retaining lugs that the face 30 of the pawl engages theopposing rounded edge 32 of the notch l9a to hold the clamping elementl3a in its normal position. When the pressure applied to the toe ironreaches some predetermined value, the rounded edge 32, reacting againstthe cam surface 38 forces the pawl out of the notch against the tensionof spring 20a to effect the release of the toe iron. It will be evidentthat the initial tension of the spring and the slope of the cam facewill determine the stress which must be applied to force the pawlrearwardly and effect release.

In Fig. 6 the spring element 25a has been turned end for end so that thesteeper cam face 3| is now engaging the rounded projection 32 of theflange I5a to hold it against lateral movement. When the spring is thuspositioned, it is evident that the stress which must be applied to thetoe iron to force the cam out of the notch will be very much greaterthan was the case in the arrangement of Fig. 5. Thus, the reversal ofthe spring 200. provides for an adjustment of the point at which theclamping element will release the toe of the ski boot. If neither of thetwo release limits of any particular spring unit 20a suits the needs ofan individual user, that unit can be easily replaced by one having itscam surfaces 38 and 3| so sloped as to provide satisfactory limits.While this form of the invention does not provide for such readyadjustment between extreme limits as that of Figs. 2 and 3, it has theoffsetting advantage of extreme simplicity and of permanence ofadjustment. There can be no accidental changing of the release limit inthe device of Figs. 5 and 6, whereas such changes can very easily occurin the structure of Figs. 2 and 3.

The complete binding must, of course, include some means for holding thetoe portion of the boot down upon the ski. If desired, a conventionalstrap 33 threaded through the slots 34 of the toe irons and extendedacross the toe of the boot may be employed for this purpose. Preferably,however, each of the toe irons is provided with a lug 35 extending alongits inner face in such position as to overlie the opposite edges of thesole of the boot near its toe to hold it down upon the cover plate 25.The vertical positions of these lugs may be readily adjusted toaccommodate soles of different thicknesses by loosening the screws 36which extend through the vertical slots in the toe irons and re-engagingthe serrations 3'! on the front end of the lugs with the matchingserrations 38 formed on the forward ends of the irons at some differentpoints, after which the screws may again be tightened. While only one ofthese lugs is shown in Figs. 3 and 4. it will be evident that asubstantially identical one will be provided on the opposite toe iron.

The resilient strap element 9 may be of any conventional construction.The one here shown comprises a coil spring 39 looped around the heel ofthe boot and secured at its opposite ends to a pair of cables 40 whichextend along the opposite sides of the ski under clips 4| to some pointforward of the toe clamping elements of the binding where they aresecured to the ski. It is usual to provide such a binding with athreaded connection 42 between one end of the spring and the adjacentcable end so that the length of the cable may be varied to suitindividual needs; and it is also usual to secure the forward ends of thecables to a toggle mechanism indicated at 43, which serves as aconvenient means for tightening the strap at the time the skis are boundto the boots and, of course, for loosening it when the skis are to beremoved. While this illustrated strap has certain advantages inproviding ready adjustment and for quick attachment, it is evident thatthe present invention is not limited to its use. Any convenient form ofstrap may be employed in its place.

Since certain changes may be made in the embodiment of the invention bya mechanic skilled in the art and without departing from the fundamentalteachings, it is intended that the foregoing shall be construed in adescriptive rather than in a limiting sense.

What I claim is:

l. A safety toe clamp for a ski binding comprising a base plate adaptedto be secured to a ski, a pair of clamping members having uprightportions disposed in spaced relation to define a recess for the toe of aski boot, at least one of said members being pivotally connected at apoint forward of its center to said base plate, and means for normallyholding said last mentioned member against swinging movement in such aposition as to confine the toe portion of a ski boot between itself andthe opposing member, said means comprising a part on said swingingmember, a pawl carried by said base plate, and a spring for urging saidpawl forwardly into engagement with said part, said part and pawl havingmutually engaged surfaces which are so sloped that lateral pressure uponsaid swinging member in excess of a predetermined limit will force saidpawl rearwardly and free said part whereby the rear end portion of themember may swing outwardly to permit the toe portion of such a ski bootto escape from the binding.

2. A safety toe clamp for a ski binding according to claim 1, furthercharacterized in that said spring comprises a leaf spring which isdisposed generally crosswise of the binding, in that said pawl issecured to said spring between its ends, and by means on said base platefor supporting said spring at its opposite ends.

3. A safety toe clamp for a ski binding comprising a pair of baseplates, a pair of clamping members each having an upstanding flangeadapted to engage the toe portion of a ski boot, and a lateral portionwhich is pivotally connected near the forward end of the member to oneof said base plates, and each such lateral portion having a shoulderformed on its rear edge, a pair of pawls each having an inwardly slopingsurface adapted to engage the complementally sloped shoulder of one ofsaid clamping members thereby to hold that member against lateralswinging movement upon its base plate, and resilient means for urgingsaid pawls forwardly into engaging relation with said shoulders of saidclamping members, said base plates being adapted to be secured to a skiwith their upstanding flanges disposed in such spaced relation asnormally to engage the sides of the toe portion of a ski boot andsupport it against lateral movement upon the ski, and said pawls beingadapted to be forced rearwardly against the tension of said resilientmeans out of engaging relation with said shoulders of said members whenthe upstanding flange portions thereof are subjected to lateralpressures in excess of a predetermined limit whereby to release saidmembers and permit them to swing about their pivots to free such bootfrom the ski.

4. A safety ski binding according to claim 3, further characterized bythe provision of means for varying the tension of said resilient means.

5. A safety ski binding according to claim 3, further characterized inthat said resilient means comprise a pair of leaf springs each securedat one end to one of said base plates, in that said pawls are carried bysaid leaf springs between their ends, and by the provision of a pair ofadjusting screws each carried by one of said base plates and engagingthe free end of one of said springs.

6. A safety ski binding according to claim 3, further characterized inthat said resilient means comprise a pair of leaf springs each carryingone of said pawls, by the provision of means on each of said base platesfor engaging the opposite ends of one of said springs, and in that eachof said pawls has a pair of cam faces of different slopes whereby whensaid spring is in one position, one of said faces is adapted to engagethe projecting portion of the adjacent clamping member and when it isturned end for end, the other of said faces is adapted to engage theprojecting portion of the member.

7. A safety ski binding according to claim 3, further characterized inthat said resilient means comprise a pair of leaf springs each carryingone of said pawls, by the provision of oppositely disposed lugs uponeach base plate for confining the opposite ends of one of said springs,and in that each of said pawls has a pair of cam faces of differentslopes whereby when said spring is in one position, one of said faces isadapted to engage the projecting portion of the adjacent clamping memberand when it is turned end for end, the other of said faces is adapted toengage the projecting portion of the member.

8. A safety ski binding according to claim 3, further characterized inthat said resilient means comprise a pair of leaf springs each carryingone of said pawls and each having its ends inturned to such an extent aspartially to overlap the main body of the spring, by the provision ofspaced lugs on each base plate between which each end of one of saidsprings may be confined, and in that each of said pawls has a pair ofcam faces of different slopes whereby when said spring is in oneposition, one of said faces is adapted to engage the projecting portionof the adjacent clamping member and when it is turned end for end, theother of said faces is adapted to engage the projecting portion of themember.

9. A safety toe clamp for a ski binding according to claim 3, furthercharacterized in that the lateral portion of each member has a roundedinner rear corner, and in that each pawl has a sloping outer surface,said rounded corner of said member and said outer sloping surface ofsaid pawl being adapted to cooperate to force the pawl rearwardlyagainst the resilient means when said member is swung inwardly from itsopen toward its normal position.

10. A safety toe clamp for a ski binding comprising a pair of baseplates, a pair of clamping members each having an upstanding flangeadaped to engage the toe portion of a ski boot and a lateral flangeportion, a pivotal connection between the forward portion of eachlateral flange and the adjacent one of said base plates, each lateralflange having a forwardly extending notch in its rear edge whichprovides an inwardly sloping vertical shoulder, a pair of pawls eachhaving an inwardly sloping surface adapted to engage the complementallysloped surface of one of said shoulders, a pair of leaf springs eachdisposed generally crosswise of one of said base plates and eachcarrying one of said pawls, means securing the inner end of each springto its base plate, and a pair of adjusting screws each threaded to oneof said base plates with its forward end supporting the outer end of theleaf spring carried by that plate and with its rear end projectingrearwardly from the clamping members.

11. A safety toe clamp for a ski binding according to claim 10, furthercharacterized by a cover plate which is adapted to overlie the lateralflange portions of said clamping members and said base plates, means forsecuring said cover plate to a ski, and means on said cover forsupporting said base plates against lateral movement.

ALEXANDER MCILVAINE,

